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Introduction to biomolecules - BIOC201 > LIPID CHEMISTRY > Flashcards

LIPID CHEMISTRY Flashcards

1
Q

what is a lipid?

A

a lipid is an organic molecule that isn’t soluble in water but soluble in organic solvents such as ether , chloroform , benzene , methanol , ethanol , etc.

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2
Q

describe the water molecule

A

the water molecule is inorganic and polar

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3
Q

lipids are …

A

non - polar

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4
Q

list the 4 major classes of biomolecules

A

lipids
carbohydrates
proteins
nucleic acids

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5
Q

what do lipids make?

A

human membranes and the bilayer[ mainly made up of lipids]

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6
Q

lipids are essential components in all living organisms such as :

A

animals , plants , insects , bacteria , fungi , etc.

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7
Q

compare lipids to carbohydrates and protein

A

lipids are lighter than carbs & proteins. 1 g lipid or fat provides 9kcal energy
1 g protein or carb provides about 4 kcal energy

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8
Q

list the lipids and their derivatives.

A

vegetable oil , butter , margarine , grease , wax , etc.

steroid hormones , fat soluble vitamins , prostaglandins , thromboxanes , leukotrines are also lipids or lipid derivatives

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9
Q

discuss the insulation function of lipids.

A

mammals , especially aquatic mammals , have most fat deposited subcutaneously[ situated or applied under the skin] which act as an insulating material to protect their body from extreme heat

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10
Q

discuss the energy function of lipids.

A

camels have a hump on their backs’ , a large deposition of fat[mostly triacylglycerol or triglyceride] that provides energy and water during long - term starvation[ 1 g fat provides 9 kcal energy and 1 g of water]

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11
Q

what is the function of creams that contain lipids?

A

creams that contain lipids prevent loss of moisture from our skin

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12
Q

what does the lipid coating in the birds’ feathers do?

A

the lipid coating in birds’ feathers protects their feathers and prevents the feathers from getting wet

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13
Q

why do lipids coat the leaves of plants?

A

to protect from against abrasion and curb the loss of moisture by evaporation

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14
Q

What do lipids work as?

A

Lipids work as s precursor of several hormones and some fat soluble & anti-oxidant vitamins[A,D,E & K]

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15
Q

What are lipids a crucial part of?

A

Lipids are a crucial part of the plasma membrane

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16
Q

Where are lipids found?

A

lipids are present in the kidneys , heart , liver , etc.

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17
Q

Lipids are found in associate with protein called lipoproteins. What do these lipoproteins work as?

A

These lipoproteins work as transporters of lipids

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18
Q

Lipids are an integral part of …

A

cell membrane

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19
Q

Lipids are classified into 5 major classes based on physical property. List the 5 major classes of lipids.

A
  1. fatty acids and their derivatives
  2. neutral esters of fatty acids and glycerols[glycerides]
  3. ionic esters of fatty acids , glycerols and phosphoric acids[phospholipids]
  4. lipids without glycerols[sphingolipids]
  5. lipids combined with proteins e.g. lipoproteins , glycolipids , cholesterol , etc.
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20
Q

What group must fatty acids contain?

A

a carboxylic[-COOH] group

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21
Q

What do fatty acids contain?

A

Fatty acids contain two ends – one hydrophilic / polar end and another hydrophobic / non-polar end

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22
Q

Why are fatty acids called amphiphilic compounds?

A

Fatty acids are hydrophilic and hydrophobic

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23
Q

Where is the carboxylic group located?

A

The Carboxylic group (-COOH) is located at the hydrophilic end

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24
Q

where is the hydrocarbon tail located?

A

the hydrocarbon tail is located at the hydrophobic end -which may contains carbon-carbon single (-C-C-) or double (-C=C-) bonds

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25
Q

How many carbons can a hydrocarbon tail have?

A

12 - 20 carbons

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26
Q

Classification of Fatty acids based on the type of carbon - carbon bond in the hydrocarbon chain:

A

Saturated fatty acids

Unsaturated fatty acids - monounsaturated fatty acids , polyunsaturated fatty acids

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27
Q

Describe saturated fatty acids at room temperature.

A

saturated fatty acids are solid and waxy at room temperature

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28
Q

what are saturated fatty acids rich in?

A

animal originated fat

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29
Q

what is the general formula of saturated fatty acids?

A

[(CnH2n+1)COOH]

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30
Q

What type of carbon - carbon bonds do saturated fatty acids contain?

A

ONLY single carbon - carbon bonds

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31
Q

what are free fatty acids[FFA] ?

A

Fatty acids which are not in esterified form

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32
Q

Most fatty acids are present in …

A

esterified form with glycerols

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33
Q

what is the carbon number in saturated fatty acids ?

A

2 - 24

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34
Q

smaller than 10 carbons fatty acids are not normally found in animal lipids. what is the exception?

A

butyric acid (CH3-CH2-CH2-COOH)

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35
Q

Give 2 examples of saturated fatty acids.

A

Palmitic acid[C16:0] , Stearic acid[C18:0]

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36
Q

Define the term unsaturated fatty acids

A

unsaturated fatty acids are fatty acids that contain at least one carbon - carbon double bond

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37
Q

The higher the double bonds , the lower the …

A

melting or boiling points

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38
Q

the solubility of unsaturated fatty acids in non - polar solvents are also better than their…

A

saturated counter parts

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39
Q

The melting or boiling points[of unsaturated fatty acids] are lower than those of …

A

their saturated counter parts

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40
Q

describe all common unsaturated fatty acids.

A

All common unsaturated fatty acids are liquid at room temperature

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41
Q

what does the total number of carbon-carbon double bonds denote?

A

The total number of carbon-carbon double bonds denotes the degree of unsaturation

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42
Q

list the types of polyunsaturated fatty acids.

A
  • Dienoic series (two – C-C – double bonds)
  • Trienoic series (three – C-C – double bonds)
  • Tetranoic series (four – C-C – double bonds)
  • Pentanoic series (five – C-C – double bonds)
  • Hexanoic series (six – C-C – double bonds)
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43
Q

how many carbon - carbon double bonds does a monounsaturated fatty acid contain?

A

1

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44
Q

where are monounsaturated fatty acids present?

A

monounsaturated fatty acids are present in the lipids of prokaryotic cell membranes

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45
Q

list 2 examples of monounsaturated fatty acids and their molecular formula

A

plamitoleic acid-C15H31COOH

oleic acid - C17H33COOH

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46
Q

give a description of a dienoic series

A

a dienoic series contains 2 carbon-carbon double bonds
example - linoleic acid[C18:2 , ∆9,12]
Melting point is -5 degrees celsius

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47
Q

give a description of a trienoic series

A

a trienoic series Contains three carbon-carbon double bonds
Such as- α-Linolenic acid (C18:3, ∆9,12,15)
γ-Linolenic acid (C18:3, ∆6,9,12)
Melting point is -10 degrees celsius

48
Q

Give a description of a tetranoic series

A

a tetranoic series contains 4 carbon - carbon double bonds
Such as- Arachidonic acid (C20:4, ∆5,8,11,14)
Melting point is -50
degrees Celsius

49
Q

give a description of a pentanoic series

A

a pentanoic Such as- Eicosapentaenoic acid (C20:5, ∆5,8,11,14,17)
Melting point is -50 degrees Celsius

50
Q

give a description of a hexanoic series

A

Contain six carbon-carbon double bonds
Such as- Docosahexanoic acid (22:6, ∆4,7,10,13,16,19)
Melting point is -50 degrees Celsius

51
Q

what are essential fatty acids?

A

fatty acids that can’t be produced in the human or animal body

52
Q

what are humans and animals dependent on for essential fatty acids?

A

Humans and animals are completely dependent on plants for these fatty acids

53
Q

list the 2 essentials fatty acids.

A 
Linoleic acid (18:2, ∆9,12)
α-Linolenic acid (18:3, ∆9,12,15)
54
Q

What are plant desaturase enzymes capable of doing?

A

plant desaturase enzymes are of providing double bonds at the ∆12 and ∆15 positions which are not possible by animal desaturase enzymes

55
Q

where are unsaturated fatty acids synthesized?

A

Unsaturated fatty acids are synthesized from their saturated equivalents

56
Q

First , saturated fatty acids are biosynthesized. when and how are double bonds introduced to the chain?

A

double bonds are introduced later in various positions

57
Q

Human and animal system cannot introduce double bonds beyond the..

A

∆9 position

58
Q

What are eicosanoids?

A

Eicosanoids are the derivatives of 20 carbon arachidonic acid (20:4, ∆ 5 , 8 , 11 , 14)

59
Q

name the 3 major classes of eicosanoids.

A
  • Prostaglandins (PG)
  • Thromboxanes (TX)
  • Leukotrines (LT)
60
Q

where are prostaglandins[PG] synthesized?

A

In all mammalian cells except red blood cells[RBC]

61
Q

where has prostaglandin synthesis been recorded?

A

Prostaglandin synthesis has been recorded in crustaceans, insects, amphibians, fish, and mammals but not in prokaryotes and lower class eukaryotes such as yeast

62
Q

Prostaglandins[circulating hormones) aren’t stored[unlike insulin]. How long are prostaglandins produced after a stimuli?

A

Prostaglandins are produced within 10-30 seconds after a stimuli

63
Q

Chemistry. what do prostaglandins contain?

A

Prostaglandins contain diverse groups such as keto (=C=O), carboxyl (-COOH), hydroxyl (-OH) which are found on the side chain or cyclopentane ring in the structure

64
Q

Prostaglandins are the derivatives of :

A

prostanoic acid

65
Q

The double bonds of prostaglandins are in the :

A

TRANS configuration

66
Q

what does the letter after the abbreviation PG indicate?

A

The letter occurring after the abbreviation PG (such as PGE) indicates the nature of the oxygen containing substituents present in the cyclopentane ring

67
Q

What the number in PGE2 represent?

A

The number 2 in PGE2 indicates that there are two double bonds present in the hydrocarbon side chains

68
Q

what are the physiological effects of prostaglandins?

A

They cause confusion

69
Q

what do prostaglandins usually work as?

A

Prostaglandins usually work as a natural mediator of fever, pains and inflammation such as- arthritis, skin or eyes inflammations etc.

70
Q

what does the release of prostaglandins in eyes after eye inflammation do?

A

Release of prostaglandins in eyes after eye inflammation can increase vascular permeability and intraocular pressure

71
Q

what are the effects of prostaglandins blocked by?

A

The effects of prostaglandins are by corticosteroid or anti - inflammatory drugs which prohibit PG[prostaglandins] synthesis

72
Q

what are the functions of prostaglandins?

A
  • Prostaglandins retain water , transport ion and regulate blood pressure
  • A Low tropical dose of some PGs can treat glucoma
73
Q

List the first 3 clinical uses of prostaglandins.

A

Prostaglandins :

  • induce child birth or abortion (PGE2 and PGF2)
  • prevent and treat peptic ulcer (PGE)
  • Act as a vasodilator during sever ischemia of limb
74
Q

List the last 3 clinical uses of prostaglandins

A

Prostaglandins

  • provides relief from pulmonary hypertension
  • treats erectile dysfunction (ED) or penile
  • rehabilitation after surgery (PGE1)
75
Q

What is thromboxane[TX] first isolated from?

A

Thromboxane[TX] is first isolated from blood platelets and also called thrombocyte

76
Q

Where did the name thromboxane come from and what is its abbreviation?

A

The Name came from the term ‘thrombosis’ and abbreviation is TX (such as TXA2, TXB2)

77
Q

What does thromboxane have?

A

Thromboxane has a six-membered ring containing an ether

78
Q

what does the letter after TX denote?

A

The letter after TX denotes the nature of oxygen containing six-membered ring and number after that denotes the number of double bonds

79
Q

what is thromboxane produced by and what does it act in?

A

Thromboxane is Produced by platelets and act in the formation of blood clots

80
Q

what does thromboxane reduce?

A

thromboxane reduces blood flow to the site of the blood clot

81
Q

what are the aspirin or aspirin type drugs[that reduce or block the synthesis of thromboxanes] usually used for?

A

Aspirin or aspirin type drugs, which reduce or block the synthesis of throboxanes, are usually used to relieve from this kind of intravascular thrombosis

82
Q

where are leukotrienes found?

A

Leukotrienes are found in the White Blood Cells (WBC) or leukocytes

83
Q

What do leukotrienes contain?

A

Leukotrienes contain

THREE conjugated double bonds

84
Q

what are leukotrienes derived from and what are they synthesized by?

A

Leukotrienes are Derived from arachidonic acid (20:4) & synthesized by several oxidase & lipoxyginase (LOX)

85
Q

The abbreviation of leukotrienes is LT and there are many kinds of leukotrienes such as:

A

LTA4, LTB4, LTC4, LTD4, LTE4 and LTF4

86
Q

what do the letters after LT & the numbers thereafter indicate?

A

The letters after LT indicate the nature of O2-containing substituents & the number thereafter indicates the number of double bonds

87
Q

what do leukotrienes cause?

A

Leukotrienes cause the contraction of smooth muscle especially in the lung

88
Q

Leukotrienes may also have inflammatory properties. what are those inflammatory properties involved in?

A

Those inflammatory properties are involved in rheumatoid arthritis

89
Q

The strong contraction of the smooth muscle of the lungs occurs due to

A

Potentially fatal allergic reactions caused by leukotrienes

This reaction is more fatal for the person who is hypersensitive to bee stings, penicillin etc.

90
Q

Clinical correlation : where would an asthmatic attack result from?

A

An Asthmatic attack may result from this contraction function by the synthesis of LTC4.

91
Q

What does the drug that inhibits the synthesis of LTC4 show?

A

The drug that inhibits the synthesis of LTC4 shows the promising effect for the treatment of asthma and is
used in the inhalers

92
Q

Name the most important reaction of the carboxyl group

A

esterification

93
Q

briefly describe what takes place in esterification.

A

In the esterification reaction , one molecule of acid and one molecule of alcohol react reversibly to yield one molecule of water and an ester.

94
Q

In hydrogenation , the h2 may be added across the double bonds on unsaturated fatty acids or their lipid parents in

A

The presence of Ni, Pt, or Pd catalysts

95
Q

why is the addition of H2 cis?

A

Both hydrogen atoms of the hydrogen molecule attack the double bond simultaneously.

This occurs because the H molecule is bound to the catalyst surface by unpaired electrons as it is the alkenes (pi bond interactions)

96
Q

example of a hydrogenation acid

A

For example – linoleic (C18:2,∆9,12) or oleic acid (C18:1,∆9) is converted to stearic acid by hydrogenation reaction.

97
Q

what is hydrogenation?

A

Hydrogenation is a TEST which may be used to determine unsaturation (number of double bonds) in a sample of fat.

98
Q

what is hydrogenation used in on a large scale? list an example.

A

On a large scale , hydrogenation is used in the manufacture of margarine. For example – a triglyceride from plant sources (oils) are hydrogenated until they become solids at room temperature and assume the consistency of butter.

99
Q

briefly describe what takes place in ozonolysis.

A

One mole of ozone (O3) can join with a double bond of an unsaturated fatty acids and initially forms an unstable ozonide with a final product of two aldehydes.

100
Q

briefly describe what takes place during the oxidation by KMnO4[at neutral pH]

A

At neutral pH, each double bond of an unsaturated fatty acid can be oxidized by KMnO4 to form a cis-Diol.

101
Q

Briefly describe what takes place during the oxidation by KMnO4(at alkaline pH)

A

At alkaline pH, double bonds of an unsaturated fatty acid can be oxidized by KMnO4 to form a mono- or di-carboxylic acid.

102
Q

Briefly describe what takes place during the oxidation by OsO4(at alkaline pH)

A

At alkaline pH , the double bonds of an unsaturated fatty acid can be oxidized by OsO4 to form a cis - diol

103
Q

PEROXIDATION OF UNSATURATED FATTY ACIDS. Describe the double bonds in polyunsaturated fatty acids.

A

The double bonds in polyunsaturated fatty acids are not conjugated

104
Q

What do successive bonds belong to?

A

Successive bonds belong to a 1,4-pentadiene system

105
Q

what does the 1,4 pentadiene show?

A

This system shows properties
which differ from those of
conjugated systems where electrons are delocalized

106
Q

what is the 1,4-pentadiene readily attacked by? when does this take place?

A

The 1,4-pentadiene system is readily attacked by molecular oxygen after generation of a free radical at the methylene.

107
Q

after molecular oxygen is added , what will it be converted to?

A

After the addition of molecular oxygen it will be converted to a conjugated hydroperoxide which will be finally converted to keto- and hydroxy-keto acids

108
Q

What is this kind of conversion of fats or lipids called?

A

This kinds of conversion of fats or lipids is called the rancidation which is inversely proportional to its quality

109
Q

what causes fats to be rancid during storage

A

During storage, fats can be rancid due to peroxide formation at double bonds with atmospheric oxygen or microbial hydrolysis when free fatty acids are released

110
Q

what do short chain fatty acids have?

A

These short chain fatty acids have some unpleasant odour and taste

111
Q

The higher the amount of short chain fatty …

A

The higher the rancidity of the fat

112
Q

How can the rancidity of fats be determined ?

taste or smell

A

by taste or smell - From the unpleasant taste or smell of fat the qualitative rancidity of fat can be determined

113
Q

How can the rancidity of fats be determined ?

titration reaction

A

By the titration of the fat with alkali such as KOH and an indicator such as phenolphthalein can quantitatively determine the level of rancidity in fat.

114
Q

How can the rancidity of fats be determined ?

acid value

A

The result of titration is called ACID
VALUE and the higher the acid
value the lower the quality of fat.

115
Q

Fat is the major component of our cell membrane. what happens if membrane function is defective?

A

It causes cell death

116
Q

How can humans protect themselves from fat oxidation?

A

by consuming foods containing anti - oxidants such as Vit-E, Vit-C, Flavonoids, Polyphenols, Carotenoids and many other phytochemicals as they work as anti-oxidants in our system to prevent cell death

Several anti-oxidative compound and enzymes such as Glutathion, Super oxide dismutase, Catalase also work as auto anti-oxidants in our system

Introduction to biomolecules - BIOC201 (6 decks)

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